Electric circuit interrupter



Jan. 3, 1939. p NowAK 2,142,860

ELECTRIC CIRCUIT INTERRUPTER Filed April '7, 1938 GAS-PRODUCING COMPOSITION 3 COMPRISING POLYBASI C ORGANIC ACID DERIVATIVE, PREFERABLY OXAMIDE.

Ihventor: Paui Nowak, b 3 44/1745. A

y His Attorney Patented Jan. 3, 1939 i UNITED STATES PATENT OFFICE 2,142,860 ELECTRIC cmcorr m'rnanurrna Paul Nowak, Berlin-Charlottenburg, Germany, as-

signor to General Electric Company, a corpo tion of New York Application April 7, 1938, Serial No. 200,798 I Germany July '19, 1937 9 Claims. (Cl. 200149) This invention relates to electric circuit interdioxide nd ni n r h are h n rupters, and more particularly to circuit interexample of such a substance is oxamide, which in rupters of the air-break expulsion type wherein the heat of the arc decomposes into ases and a gas formed by decomposition of a material by vapors, leaving practically no residue. This subthe are upon opening of the circuit is utilized to Stance has the property of being less hygroscopic 5 interrupt the arc. than oxalic acid, which is used in accordance with In a well-known form of circuit interrupter of Burmeister U. S. Patent 2,089,050 in constructing the aforesaid type, the arc is drawn in a confining -c fi ng S ct e am d gives Off insulating structure, such as a tube formed of sufficient carbon dioxide and nitrogen in the are 10 material which under the influence of the are heat to quickly extinguish the arc. 10

emits gases or vapors tending to extinguish the My invention will be set forth more fully in the arc. Inorganic materials such, for example, as following description referring to the accompanyboric acid, ammonium alum, etc., have been proing drawing, and the features of novelty which posed as the gas-producing material. In these characterize my invention will be pointed outwith substances water is chemically combined so that, particularity in t e ms a e ed to a d form 15 under the influence of the arc, vapors are released ing a part of this specification. for the arc-extinguishing process. It has also Referring to the drawing the single figure therebeen proposed to use aminoplasts (general term of is an elevational view, partly in section, of an for synthetic resins from amido or amino comelectric circuit breaker of the expulsion type to pounds) in the construction of arc-confining which the present invention is applicable. 20 structures. Aminoplasts contain nitrogen which There is shown merely by W y Of example an is evolved under the are heat and tends to extinric circuit int rrup r, m p ul rl a guish the arc. More recently, other gas-procircuit breaker having means such as the stationsame have come into prominence for making arc- Opening the circuit so as to form an arc, and an 25 insulating members. For example, in Burmeister insulating structure 3 forming an arc chamber for U. S. Patent 2,089,050 is disclosed and claimed an closely confining the are between the contacts.

and in Burmeister U. S. Patent 2,089,051, memember closed at the fixed contact end and open chanically strong organic material, for instance at the other end for receiving the rod contact. 30 hard rubber, impregnated with an inorganic ma- Upon opening of the circuit, separation of the terial which upon decomposition yields an arccontacts I and 2 causes formation of anarc which nterrupting gas and, specifically, with ammodecomposes some of the material of the arc nium carbonate or bicarbonate, calcium carbonchamber walls 3. The gas so formed is under :5 ate, etc. Reference is also made'to the copendconsiderable pressure by reason of the comparaing applications of Rudolf Auerbach and Hertively' close fit of the rod contact 2 and the tube mann Burmeister, Serial No. 200,770, filed April 3, with the result that when the rod leaves the 7, 1938 of Hans Schuhmann, Serial No. 201,410, tube a. blast of gas is released as indicated for filed April 11, 1938 and of Vitaly Grosse, Serial No. in rrupting the a e.

49 200,784, April 7, 1938, all of which applications The beneficial effects of amides as arc-inter- 40 are assigned to the same assignee as the present rupting materials may be obtained in a variety of invention. In these co -pending applications ways. In accordance with a preferred embodiother solutions to the same general problem of ment of the invention anamide or a diamide of a improving circuit interrupters of 'the air-break n lybasic carboxylic acid, m p r yan expulsion type are disclosed and claimed. amide of a saturated dibasic carboxylic acid, for 45 In accordance with the present invention, eleca ple oxamide, succinamide or the like, is tric circuit interrupters having insulating strucemployed as a filling material for artificial resins, tures disposed adjacent and in confining relation p u ar y aminopl s Such, example, as to an are formed upon opening the circuit comureaor thio-urea-formaldehyde condensation lo prise a polybaslc organic acid derivative which products. The insulating structure 3 is formed is normally solid (that is, solid at room tempera of, or has its inner portion surfaced with a comture) and is capable of evolving an arc-interruptposition comprising such filled resinous mass. By ing gas in the heat of an arc. I prefer to use a using such filling material the mechanical properdlbasic carboxylic acid derivative which is capaties, for example the tensile and impact strengths, ble of evolving nitrogen, preferably both carbon or the shaped, hardened mass are improved. 56

provement in strength of the structure is accompanied by an improvement in arc-extinguishing properties. Thus, effective arc-quenching tubes of a size and strength to meet a wide variety of service conditions may be made.

Besides aminoplasts, other artificial resins may be used as the basic material for constructing the walls of the arc-extinguishing chamber. For example, I may suitably combine oxamide or the like with a modified or an unmodified alkyd resin as, for example, a modified or unmodified glyceryl-phthalate alkyd resin. An electric circuit interrupter comprising an insulating structure having walls comprising alkyd resin is disclosed and broadly claimed in the aforesaid co-pending application of Hans Schuhmann, Serial No. 201,410, and I make no broad claims to such insulating structures.

In addition to a normally solid amide or diamide, other filling materials may be incorporated in the artificial resin as desired or as conditions may require. For instance, in certain cases it is advantageous to incorporate in the resin a material capable of giving ofi oxygen under the arc heat, for example an inorganic peroxide as, for instance, magnesium peroxide, barium peroxide, and the like.

It is also possible to use an amide or a diamide of a polybasic carboxylic acid, for example oxamide, as the sole or main component of the walls of the arc-confining member. The powdered amide, with or without suitable binding or other additional materials, is shaped under high pressure. As examples of binding agents which may be used, I mention inorganic binders such as plaster of Paris, clay, etc., and organic binders such as highly oxidized oils, for instance linseed and China-wood oils, or prepolymerized artificial resin as, for example, an aminoplast.

A mechanically strong reinforcing tube composed, for instance, of a suitable fibrous material such as hard fiber, wool, paper, linen, etc., may be provided with an inner liner comprising oxamide or the like. Reinforcing materials of this kind also may be impregnated, in any suitable manner, with such amides or with compositions containing the same. Thus, the amide may be dispersed in, or emulsified with aminoplasts dissolved or colloidally suspended in water or other solvent, and the resulting composition used as an impregnant for the fibrous or other base material of which the insulating structure is formed. Thereafter the solvent is removed.

If the arc-quenching chamber is provided with a coaxially-arranged insulating filling member or pin, then the walls of such member exposed to the arc heat also may be made of materials such as hereinbefore described with reference to a main arc chamber or insulating tube.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric circuit interrupter comprising means for forming an arc, and an insulating structure disposed adjacent and in confining relation to said arc, the walls of said structure in proximity to said arc being surfaced with a composition comprising an amide of a saturated dibasic carboxylic acid.

2."An electric circuit interrupter comprising means for forming an arc, and an insulating tubular structure within which said are is drawn, said tubular structure being in confining relation to said arc and having walls in proximity to said arc surfaced with a composition comprising oxamide.

3. An electric circuit interrupter including an arc-confining structure, the walls of said structure in proximity to said are being surfaced with a composition comprising mechanically strong artificial resin filled with an amide of a saturated dibasic carboxylic acid.

4. An electric circuit interrupter including an arc-confining structure, the walls of said structure in proximity to said arc being formed of a composition comprising a mechanically strong artificial resin, oxamide and a material capable of giving on" oxygen under the are heat.

5. An electric circuit interrupter comprising means for forming an arc, and an insulating structure disposed adjacent and in confining relation to said arc, the walls of said structure in proximity to said are comprising an aminoplast and oxamide.

6. An electric circuit interrupter including an arc-confining structure, said structure consisting of a composition comprising an aminoplast filled with oxamide andan inorganic peroxide.

'7. An electric circuit interrupter comprising means for forming an arc, and an insulating structure disposed adjacent and in confining relation to said arc, said structure consisting of a composition comprising an alkyd resin and oxamide.

8. An electric circuit interrupter including an arc-confining structure, said structure consisting of a composition comprising a glyceryl-phthalate alkyd resin filled with oxamide and magnesium peroxide.

9. An electric circuit interrupter comprising means for forming an arc, and an insulating structure disposed adjacent and in confining relation to said arc, the walls of said structure in proximity to said arc being surfaced with a composition comprising an amide of a saturated dibasic carboxylic acid and a material capable of giving ofi oxygen under the arc heat.

- PAUL NOWAK. 

